Swallett

A wizard who was described as "old" when the Lecturer in Recent Runes was a student at Unseen University. "Bogeyboy" Swallet led an expedition (of students, including the Lecturer) to find the Lost Reading Room in the Library. They wandered around the Library for three weeks, eating their own boots; fortunately, they found the remains of the previous year's expedition (and ate their boots too). Eventually, they made it out of the Library.

The Lecturer in Recent Runes reminisces about Swallet and his expedition in The Last Continent, when the Librarian is sick and the Library's books are out of control.